Method of mounting ball-bearing tracks for revolving cranes and the like



June 19, 1962 HElGL METHOD OF MOUNTING BALL-BEARING TRACKS FOR REVOLVINGCRANES AND THE LIKE Filed March 15, 1961 INVENTOP A TERA/5):;

United States Patent Ofi ice Patented June 19, 1962 3,039,730 lVIETHODOF MOUNTING BALL-BEARING TRACKS FOR REVOLVING CRANES AND THE LIKE GeorgHeigl, Ulm (Danube), Germany, assignor to Wilhelm Reich,Maschinenfabrik, Neu-Ulm, Bavaria, Germany Filed Mar. 15, 1961, Ser. No.95,965 Claims priority, application Germany Mar. 19,1960 8 Claims. (Cl.248346) chines are usually mounted on ball-bearing tracks or turntablesin order to turn or swivel the entire machine very easily on anundercarriage or frame. Depending upon the size of the respectivemachines, these ball bean'ng tracks or turntables may be of very largediameters and amount to several meters. Such a track or turntable mustbe mounted absolutely evenly and level at all points on its supportingframe.

It is, however, a very difiicult procedure to produce such a largesupporting frame with an absolutely level surface. This either requiresvery large machine tools or, since such machines are usually notavailable for this specific purpose, the ball-bearing track must beleveled by means of shims, base plates, and. the like. This is, however,not only a very diflicult and timeconsuming procedure, but usually sucha supporting structure will not stand up very long under the heavy anduneven loads and stresses to which it is subjected by the operation ofthe crane or other machinery. When such a supporting frame becomesuneven, the result will be that the ballbearing track or turntablecarrying the crane or other machine will become distorted and may thenbe turned only with difficulty, or that the balls of the ball bearingmay become wedged or damaged or that they may break entirely.

It isthe object of the present invention to provide a method of mountinga ball-bearing track or turntable for a revolving crane, excavator orother heavy machine on a supporting frame on which a plurality ofsupporting members are secured in a polygonal or circular formation inaccordance with the diameter of the ball-bearing track or turntablewhich is to :be mounted thereon. According to the invention, the upperflanges of the supporting frame are coated with a layer of a suitableembedding material which is capable of hardening, and before this layerhas hardened, a number of mounting plates are applied thereon in theproper formation in accordance with the diameter of the ball-bearingtrack which is later to be secured thereto. These mounting plates arethen pressed into the embedding layer in such a manner that the finishedsurfaces of the plates will be perfectly level and at all points withinthe same plane. After the embedding material has hardened, theball-bearing track may be properly secured to these plates and to theflanges of the supporting frame.

The embedding material to be used according to the invention consists ofa hardening plastic, for example, polyester, which is reinforced withmetallic fillers, for example, cast-iron or other metal powder, smal1steel chips, or the like.

In order to secure the mounting plates in the proper position to thesupporting frame, these plates are first temporarily mounted by means ofbolts on the lower side of an auxiliary leveling ring which is machinedand finished on both sides and may be reused as often as desired forsimilar installations. After a layer of the mentioned embedding materialhas been applied upon the surface of the upper flanges of the supportingframe, and before this material has hardened, the leveling ring with themounting plates connected thereto is placed upon the embedding layer andpressed into the same in such a manner that the surface of the levelingring is abso lutely level. After the embedding material has hardened,the mounting plates are secured to the supporting frame, for example, bybeing welded thereon along their sides, whereupon the leveling ring isunbolted and removed from the mounting plates.

By proceeding according to this method, it will be insured that theupper surface of the mounting plates will be perfectly plane and level,and that during the subsequent operation of the crane or other machinethe ballbearing track or turntable of this machine which is secured tothese mounting plates will never tilt, become distorted or yield in anyother Way. The new method of producing the supporting frame has thefurther, very important advantage that it is very simple and economicalsince it does not require any special machinery and since the auxiliaryleveling rings may be frequently used.

The above-mentioned as Well as additional features and advantages of thepresent invention will 'become further apparent from the followingdetailed description thereof which is to be read with reference to theaccompanying sheet of drawings, in which FIGURE 1 shows a perspectivetop view of a supporting frame according to the invention; while FIGURE2 shows an enlarged cross section taken along line IIII of FIGURE 1.

The supporting frame for receiving a ball-bearing track or turntable,not shown, for a revolving crane or a similar machine consists generallyof a plurality of beams 1 of a U or double T-shaped cross section whichare welded together to a polygonal shape. In the finished condition,rectangular or segmentaily shaped mounting plates 2 are secured upon theupper flanges of beams 1 in a polygonal or substantially annulararrangement. These mounting plates 2 as well as the upper flanges ofbeams 1 underneath the same are provided with bores 3 which subsequentlyserve for receiving bolts for securing the stationary part of theball-bearing track. A supporting frame of this kind which is subjectedto very high mechanical stresses must have mounting plates 2 withabsolutely plane and level upper surfaces so that the ball-bearing trackmay be properly secured thereon.

It is a fact, well-known in this art, that it is very difiicult toprovide supporting frames for ball-bearing tracks or turntables forrevolving cranes, excavators, or the like, which are made of individualbeams 1 which are welded together, with a sufficiently level surface.This is due partly to the distortions caused by welding and partly tomanufacturing inaccuracies in the shape and dimensions of the beams ofwhich the supporting frame is assembled. A special mechanical levelingor finishing treatment of the supporting frame is therefore alwaysrequired.

In order to carry out this leveling treatment as easily and quickly aspossible, the present invention provides a special leveling ring 5 whichis finished on both outer sides so as to have absolutely plane surfaces.This ring 5 which may be reused for as many frame installations asdesired is made of a diameter equal to the diameter of the ball-bearingtrack. It is provided along its periphery with a number of bores. 7which are spaced from each other at a distance corresponding to thedistance between the bolts by means of which the ball-bearing track isto be later secured. Into these bores 7, bolts 6 are inserted andscrewed into the tapped bores 3 in the mounting plates 2 so that thelatter will be fixed in the proper final position on the lower side ofring 5. Mounting plates 2 are preferably factory-made so as to be of anequal thickness and to have finished outer surfaces.

After the mounting plates 2 are secured to leveling ring 5, a layer 4 ofa suitable embedding material is applied upon the upper fianges ofbeams 1. Before this embedding material 4 starts to set, the mountingplates 2 on ring 5 are applied thereon and pressed into the embeddingmaterial so that the upper surface of ring 5 will be absolutely level.Any unevenness on the surface of frame 1 will thus be leveled by beingfilled out by the embedding material 4.

After the embedding material 4 has hardened, any excess thereof isremoved mechanically, whereupon the individual mounting plates 2 areadditionally connected to beams 1, for example, by welding them theretoalong the sides, as indicated in FIGURE 2. It is for this purpose onlynecessary to attach the mounting plates 2 by spot Welding to insure thatthey will remain in the proper position on beams 1.

Thereupon, bolts 6 are loosened and leveling ring 5 is removed from themounting plates 2. Since the bores 3 in plates 2 are already in theirproper final position, it is only necessary to drill them out to thediameter of the mounting bolts of the ball-bearing track which are laterto be inserted, and also to drill through the layer of embeddingmaterial 4 below and through the fianges of beams 1. After theball-bearing track is bolted on, it will be solidly connected to thesupporting frame by means of mounting plates 2 and the hardenedembedding material 4, and it will rest absolutely plane and level on theframe.

As already indicated, it is also possible, instead of applyingrectangular mounting plates 2 in a polygonal arrangement, to providesegmentally shaped plates which may be assembled to form a completering. If a ballbearing track of a smaller diameter is to be mounted, itis also possible to' apply a fully machined and finished mounting ringof a single piece of material which is then pressed into the layer ofembedding material 4. In this case, it will not be necessary to use aleveling ring 5.

The embedding material 4 preferably consists of a suitable plastic, forexample, polyester, which is adapted to harden quickly and very solidly.It is advisable to reinforce this embedding material with suitablefillers, preferably of a metallic type, for example, cast-iron powder orother metal powder, small steel chips, or the like.

After hardening, this embedding material 4 has a very high compressivestrength, and any squeezed out excess may then be easily filed, groundor chipped off. It hardens to such an extent that no material can besubsequently squeezed out by the weight under which the mounting plates2 press upon the layer 40f embedding material on flanges 1 during thelater operation of the machinery which is mounted on the'ball-bearingtrack, and this is true even though the layer 4 may at different pointshe of different thicknesses or only very thin in accordance with theuneven surfaces of frame 1 which are leveled out by. this layer. 7

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof, I wish to have it understood thatit is in no Way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the ap- V pendedclaims.

Having thus fully disclosed my invention, what I claim is:

1. Amethod of mounting a ball-bearing track or turntable of a revolvingcrane, excavator, or other machine on a supporting frame composed ofbeams secured to mounting plates for subsequently supporting theballbearing track upon the embedding layer before said layer hardens andin the proper position in accordance with the diameter of theball-bearing track, and then pressing said mounting plates into theembedding layer to a depth so that the finished upper surfaces of saidplates will be absolutely level and disposed at all points within thesame plane.

2. A method as defined in claim 1, in which said embedding materialconsists of a suitable hardening plastic with reinforcing metallicfillers therein.

3. A. method of mounting a ball-bearing track or turntable of arevolving crane, excavator, or other machine on a supporting framecomposed of beams, secured to each other in a polygonal shapesubstantially in accordance with the diameter of the ball-bearing trackto be mounted thereon, comprising the steps of temporarily securing aplurality of mounting plates by means of bolts to the lower side of anauxiliary leveling ring which is finished on both sides, and in thecorrect final position of said mounting plates relative to each otherand in accordance with the diameter of the ball-bearing track to belater secured thereto, then applying a layer of a hardening embeddingmaterial upon the upper surfaces of the supporting frame, then placingsaid mounting plates while mounted on said leveling ring upon theembedding layer before said layer hardens, then exerting a pressure uponsaid leveling ring so as to press said mounting plates into saidembedding layer to a depth so that the upper surface of said ring willbe absolutely level and the finished upper surfaces of said plates willbe disposed at all points within the same plane, and then unbolting andremoving the leveling ring from said mounting plates after saidembedding layer has hardened.

4. A method as defined in claim 3, further comprising the step ofdrilling out the bores in the mounting plates previously containing thebolts for attaching said plates to the leveling ring, and also drillingthrough the hardened embedding layer and through parts of the supportingframe so as to form bores for the subsequent insertion of mounting boltsfor securing the ball-bearing track to said supporting frame.

5. A method as defined in claim 3, further comprising the step ofadditionally securing said mounting plates to the upper parts of saidsupporting frame by'welding said plates at their sides to said frameafter said embedding layer has hardened and before said leveling ring isunbolted and removed from said mounting plates.

6. A supporting frame for a ball-bearing track or turntable of arevolving crane, excavator, or other machine, comprising a pluralityof'beams secured to each other in a polygonal shape substantially inaccordance with the diameter of the ball-bearing track to be mountedthereon, a layer of a hardened embedding material adhering to the uppersurfaces of said beams, and a plurality of fiat mounting plates at leastpartly embedded in said layer so that the upper surfaces of all of saidmounting plates are level and disposed at all points within the sameplane;

7. A supporting frame as defined in claim .6, in which said embeddinglayer consists of a suitable plastic .containing reinforcingmetallicfillers.

8. A supporting frame as defined in claim 6, further comprising meansfor additionally securing said embedded mounting plates to the upperparts of said beams, said means comprising Welds on the sides of saidmount- 7 ing plates.

References Cited in the file of this patent 'UNITED STATES PATENTS596,280 Short Dec. 28, 1897 1,893,699 Dunning Jan. 10, 1933 2,423,869 7Blessing July .15, 1947 2,931,684 Johnson Apr. 5, 1960

